Ripping customers off!!!

DSTV failed to resolve my WIFI issue after a month of going back and forth with them I asked them to cancel my contract and come fetch their router of which they did. Now they are refusing to give me my refund or cancel the contract, they just contacted me about a debit order due on the 26th for a service I’m not using. They agreed on mail to cancel the contract and refund me for the WIFI as it never worked and now they are planing to debit my account